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Subsets0078.java
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39 lines (30 loc) · 942 Bytes
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import java.util.ArrayList;
import java.util.List;
/**
* leetcode回溯法：子集
* 该题比较难，回溯算法的精髓在于平行宇宙的概念（自创的）
*/
public class Subsets0078{
public static void main(String[] args) {
int nums[] = {1,2,3};
subsets(nums);
}
private static List<List<Integer>> result = new ArrayList<List<Integer>>();
public static List<List<Integer>> subsets(int[] nums) {
List<Integer> tmp = new ArrayList<>();
backtrack(nums, 0, tmp);
return result;
}
private static void backtrack(int[] nums, int start, List<Integer> tmp) {
result.add(new ArrayList<>(tmp));
for (int i = start; i < nums.length; i++) {
tmp.add(nums[i]);
backtrack(nums, i+1, tmp);
tmp.remove(tmp.size()-1);
}
for (int j : tmp) {
System.out.print(j + " ");
}
System.out.println();
}
}